Bad Mildew smell A/C leak or something else?

[TVbuster]

Hey everyone, I could use some help. I'm not sure if this is the best section for this post but my 2017 GTI has developed a bad mildew smell over the past 2 months. I didn't know what it was for a while but now it's noticeable. Even if I leave a bag or something in my car overnight, bring it inside, the bag will smell like mildew.

I did some research and found that some people say the AC drain hose is "loose" from the factory and allows water to leak. I do use my A/C frequently, even in the winter, to help defrost the car. So I removed the carpet and checked the foam. The foam area near the A/C drain hose did seem to smell and it seemed to be the strongest source I could smell. And I noticed there was a darker yellow line as if some water had been leaking but it was only slightly damp. I ran the AC for 10 minutes with a paper towel placed in this area and it did not have a drop of water on it. But you can see the yellow area in the pictures and it's above the drain so maybe it's leaking higher up. But I thought the paper towel test would be a good one.

I put some bleach/water mix on that area to try to clean it and remove the smell and I have not been using my A/C for about a week. It seems like it's gotten slightly better but it's hard to say. It could be my nose playing tricks on me. But I also replaced my cabin air filter for the first time in 3 years (i know, bad) and first time in 50,000 miles. The old one had some leaves on it but didn't smell like mildew.

I also bought klima klean and I'm gonna spray it in there soon.

Does anyone have any thoughts based on my pictures where this leak could be coming from?

 

[gixxerfool]

These cars have some common sources fir leaks.
-Check the sunroof drains for clogs
-Rear door speaker seals fail and leak into the car
-Rear body vents behind the rear fascia allow water ingress
-the emblem drain in the hatch tends to rot and allow water in.

 

[TVbuster]

These cars have some common sources fir leaks.
-Check the sunroof drains for clogs
-Rear door speaker seals fail and leak into the car
-Rear body vents behind the rear fascia allow water ingress
-the emblem drain in the hatch tends to rot and allow water in.

I don’t have a sunroof so I can rule that out haha.
But thank you for the ideas. I’ll look into these areas. I’m not sure what you mean about the rear body vents behind the rear fascia. Are these under the trunk liner on the floor?

 

[gixxerfool]

I don’t have a sunroof so I can rule that out haha.
But thank you for the ideas. I’ll look into these areas. I’m not sure what you mean about the rear body vents behind the rear fascia. Are these under the trunk liner on the floor?

No. These are the vents that allow pressure to escape when closing doors and such. They are literally behind the rear bumper and As far as I know only accessible by removing the fascia. There are plenty of threads between here and the vortex about the issues I mentioned. You should be able to find plenty of documentation.

 

[Urlik]

Use this: https://www.amazon.com/nextzett-961...ocphy=9027555&hvtargid=pla-548798885674&psc=1
Put blower on manual, turn fan on high and dash vents selected, shove hose in middle vents down to the condensor and spray away. I do it once a year. You'll see it drain out the drain.

 

[TVbuster]

Use this: https://www.amazon.com/nextzett-961...ocphy=9027555&hvtargid=pla-548798885674&psc=1
Put blower on manual, turn fan on high and dash vents selected, shove hose in middle vents down to the condensor and spray away. I do it once a year. You'll see it drain out the drain.

Ok great, I actually ordered some of that and plan on trying it soon. Thanks for that.

 

[CKIVSEPA]

I have a similar smell issue, but when a hurricaine came through my car seemed to bring in a little water.
I noticed the floor behind the driver seat was damp after picking the car up from the shop.
I could run that A/C product, but I wonder if my foam under the carpeting is damp?

The smell seemed to go away during the cold months here in PA, but as the temps have come above 50, the smell is back. Hmmm?

 

[gixxerfool]

I have a similar smell issue, but when a hurricaine came through my car seemed to bring in a little water.
I noticed the floor behind the driver seat was damp after picking the car up from the shop.
I could run that A/C product, but I wonder if my foam under the carpeting is damp?

The smell seemed to go away during the cold months here in PA, but as the temps have come above 50, the smell is back. Hmmm?

You may have actual water ingress. There’s a ton of info on the regular problems for these cars, the long and short of it is:
-rear door woofers seals are leaking
-rear body vents behind the fascia is leaking
-hatch emblem drain tube is broken

of course you could have sunroof drain issues or something else going on, but these are the common culprits.

 

[ZuMBLe]

Use this: https://www.amazon.com/nextzett-961...ocphy=9027555&hvtargid=pla-548798885674&psc=1
Put blower on manual, turn fan on high and dash vents selected, shove hose in middle vents down to the condensor and spray away. I do it once a year. You'll see it drain out the drain.

I just used this and it worked well!

 

[TVbuster]

Just an update. It was the rear door speaker seals. I sealed them up but it was too late. The insulation under the carpet was soaked. It’s been a couple months and I did everything except cut out the insulation and the car now has a weird smell. I bought an ozone machine, steam cleaner, I dried the insulation with industrial sized fans and lifted up the carpet for about 4 days, tried baking soda in my entire interior, asked VW for support, nothing. After 5 ozone treatments and all that it still has a weird smell that comes and goes. Do you think I should try going to a legit detail shop instead of just trying to do it myself? OR cut out the insulation under the rear carpets and try to fit new insulation in there from Amazon. And yes I’m 100% sure the leak is gone. It doesn’t smell like mildew much anymore. But it’s just the residual effects. It sucks because I have always kept this car pristine and 100% mint.

 

[gixxerfool]

You buy rolls of jute. Sometimes lifting the carpet isn’t enough. You need to remove it. There isn’t a great way otherwise to get to anything. I would pull the carpets, make sure there isn’t any damp spots remaining and then pull the old jute and replace it with new.

For odor removal buy a bag of ground coffee open it and either put it in a larger container so I won’t spill or leave it in the bag, but a few days and it should pull a good portion of odors out.

The headliner may have soaked up some of th smell and they’re difficult to deodorize effectively.

 

[TVbuster]

You buy rolls of jute. Sometimes lifting the carpet isn’t enough. You need to remove it. There isn’t a great way otherwise to get to anything. I would pull the carpets, make sure there isn’t any damp spots remaining and then pull the old jute and replace it with new.

For odor removal buy a bag of ground coffee open it and either put it in a larger container so I won’t spill or leave it in the bag, but a few days and it should pull a good portion of odors out.

The headliner may have soaked up some of th smell and they’re difficult to deodorize effectively.

Thanks for the help! Is jute another name for the insulation under the carpet? I’d rather not pull apart the front center console and stuff so maybe I will cut just the rear “jute” and replace.
I am running the ozone machine for 1 hour and 10 minutes now.
previously I only ran it for 45 minutes max. I’m gonna try a longer treatment to see if it helps. Maybe I should just do two hours.

 

[gixxerfool]

Thanks for the help! Is jute another name for the insulation under the carpet? I’d rather not pull apart the front center console and stuff so maybe I will cut just the rear “jute” and replace.
I am running the ozone machine for 1 hour and 10 minutes now.
previously I only ran it for 45 minutes max. I’m gonna try a longer treatment to see if it helps. Maybe I should just do two hours.

Correct. Sometimes it is plastic backed I’m not sure about VWs offering.

 

[KyACRASH]

I had a similar experience with a leak that ruined the insulation. I replaced the carpet and insulation.

ebay - OEM insulation

ebay - carpet

 

[TVbuster]

Thank you. Just to follow up I replaced the carpet and insulation. It wasn’t actually THAT difficult. Should have done it first.

But I am noticing water on the door sills after heavy rain. So I removed the door card and had a friend spray the hose at the window for 2 minutes and then water started dribbling through the hole that I have circled. My question is - can I seal thay hole up? There was no water coming from around the speaker now.